A human papillomavirus infection marker predicts good survival for patients with oropharynx and unknown origin carcinoma regardless of extracapsular spread

medwireNews: For patients with oropharynx squamous cell carcinoma (OPSCC) or carcinoma of unknown primary site (CUP), research suggests that human papillomavirus (HPV) status is a significant predictor of survival, regardless of extracapsular spread (ECS) of metastatic lymph nodes.

“The results of the present study add to a small but compelling body of literature suggesting that, among patients with OPSCC or CUP who are p16 positive, the finding of ECS on neck dissection pathology does not adversely affect survival outcomes”, say Patrick Sheahan, from South Infirmary Victoria University Hospital in Cork, Ireland, and co-workers.

Their study included 62 OPSCC patients and 21 CUP patients undergoing neck dissection, 45 of whom had a positive p16 immunohistochemistry test – a marker for HPV infection. Fifty-one patients had ECS of metastatic lymph nodes, including 43 cases of extensive disease, defined as macroscopically visible tumour outside of the lymph nodes, matted nodes, or soft-tissue deposits. Patients were also considered for adjuvant treatment, with postoperative radiotherapy or chemoradiation.

Both recurrence-free survival and disease-specific survival were significantly poorer in patients who were p16-negative (hazard ratio [HR]=9.4 and 16.8, respectively) and who had ECS (HR=6.5 and 8.3, respectively). T3/4 classification, heavy alcohol consumption and smoking were also significant predictor of poor survival outcomes.

However, when patients were stratified by p16 status, ECS only significantly predicted poor recurrence-free survival and disease-specific survival in p16-negative patients, with HRs of 9.7 and 8.7, respectively, versus corresponding values of 1.1 and 1.2 for their p16-positive counterparts.

Patrick Sheahan et al highlight the “excellent survival outcomes” of the p16-positive patients, including those with extensive ECS, despite most ECS patients undergoing radiotherapy alone rather than chemoradiation.

They therefore conclude that the study’s results “are likely to be of importance not only in guiding future recommendations for postoperative adjuvant treatment in p16-positive OPSCC and CUP but also in influencing initial treatment decisions.”